The present invention relates to a remotely-controlled relay. FIG. 9 shows a conventional remotely-controlled relay. A micro-switch 18 is placed at position b shown in FIG. 10. A leaf spring 20 urges the actuator 21 of the switch 18 through an insulator 10. When an operating switch 40a is placed to the ON side, an operating current flows through a loop of diode 19b--coil 3--contact ON--D2--power source, so that the coil 3 produces a magnetic flux in such a direction as to weaken the flux of a permanent magnet 7. The magnetic flux produced by the coil 3 repels the attracting force of the fixed core 22 in abutment relation with a yoke 6 and attracts a plunger 8, as well as overcomes the force of a compressed spring 9 to release the plunger 8 to the left. Thus, the plunger 8 closes the contacts 11 and 14 of the main circuit. The insulator 10 releases the leaf spring 20, which in turn causes the switch 18 to be positioned to the position a in FIG. 10.
With the main circuit closed, when the switch 40a is placed to the OFF position, the operating current flows through a loop of D1--contact OFF--coil 3--diode 19a--power source, so that the coil 3 produces a magnetic flux in such a direction as to strengthen the flux of a permanent magnet 7. This magnetic flux increases the attracting force of the yoke that attracts the plunger 8, and overcomes the repulsive spring of a compressed force 9 to move the plunger 8 to the right, thus opening the contacts 11 and 14 of the main circuit. The insulator 10 again drives the leaf spring 20 so that the switch 18 is again positioned to the position a in FIG. 10. With this type of bistable polar electromagnet device, the stroke of movement of the plunger determines the gap between the main contacts when they are opened. However, the larger the stroke, the higher the operating current required.